Thanks for the replies, gents. This is only my second build (first was a tele style and super easy to wire) so the double neck with the three switches has required a lot of research and watching videos. Not many out there for the double neck. I used the Pitbull diagram you referenced but also checked out a couple others just to compare.

I haven't got the neck/strings on yet and was only testing with the tap test, and found that the 6 string pickups, when both at full volume was significantly less. I have to admit, being new to this I didn't even know that there were differences between the bridge and neck pickups, I just used the ones based on the wire lengths to reach the switch. It was the opposite of the diagram (the red wires were shorter so ended up being used in the neck slots, the yellow wires were longer and went into the bridge position).

I did put in the cavity shielding, and I am pretty pease so far that there is no buzzing noise as of yet when it is plugged in, but again that is without having strings on yet.

Since posting I went over all the wiring and the soldering joints and re-soldered a few. I noticed that the blue wire from the switch to the pots on the 6 string side must have got nicked by the soldering iron as there was a bit of a melt through the plastic so I replaced that and its is noticeably better and closer now to the 12 string volume, but still not as loud for sure.

I bought the multimeter, but still haven't figured out the best way to use it! Been watching videos trying to figure out what the best readings are for the different points in the circuit.

Thanks again for the feedback. Simon, you gave me lots to consider working with the pickups. I didn't really think too much about checking them before I popped them in. Rookie mistakes....

Now I have to tackle the bridge problem....the holes were drilled too narrow by 2 or 3mm and so the bridge will not come close to sitting on the posts...

Any thoughts on that one or is that a whole new thread altogether? I did discover this in the mock build but thought I would save it until later....another rookie mistake I am sure